H3C S3100 Series Command Manual page 257

undo stp interface interface-list config-digest-snooping
View
System view, Ethernet port view
Parameters
interface-list: Ethernet port list. You can specify multiple Ethernet ports by providing this argument in the
form of interface-list = { interface-type interface-number [ to interface-type interface-number ] } &<1-10>,
where &<1-10> means that you can provide up to 10 port indexes/port index ranges for this argument.
Description
Use the stp config-digest-snooping command to enable the digest snooping feature. Use the
undo stp config-digest-snooping command to disable the digest snooping feature. Configured
in system view, the setting takes effect globally; configured in interface view, the setting takes
effect on the current port only.
Use the stp interface config-digest-snooping command in system view to enable the digest
snooping feature on specific ports. Use the undo stp interface config-digest-snooping
command in system view to disable the digest snooping feature on specific ports.
The digest snooping feature is disabled by default.
To enable the digest snooping feature successfully, you must first enable it on all the switch ports that
connect to the other manufacturer's switches adopting proprietary spanning tree protocols and then
enable it globally.
According to IEEE 802.1s, two interconnected switches can interwork with each other through MSTIs in
an MST region only when the two switches have the same MST region-related configuration. With
MSTP enabled, interconnected switches determine whether or not they are in the same MST region by
checking the configuration IDs of the BPDUs between them. (A configuration ID contains information
such as region ID and configuration digest.)
As some other manufacturers' switches adopt proprietary spanning tree protocols, they cannot
interwork with other switches in an MST region even if they are configured with the same MST
region-related settings as other switches in the MST region.
This kind of problem can be overcome by implementing the digest snooping feature. If a switch port is
connected to another manufacturer's switch that has the same MST region-related settings but adopts
a proprietary spanning tree protocol, you can enable the digest snooping feature on the port that will be
receiving BPDU packets from another manufacturer's switch. Then the switch considers these BPDU
packets to be from its own MST region and records the configuration digests carried in the BPDU
packets received from the switch, which will be put in the BPDU packets to be sent to another
manufacturer's switch. In this way, the switch can interwork with another manufacturer's switches in an
MST region.
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